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#### Use TRAX Calibration check box

(This item pertains to the Probe Utilities dialog box, accessible through Insert | Hardware Definition | Probe.)

When calibrating an analog probe on some machine types, particularly when using the Leitz interface, there is typically a choice of whether or not to use the TRAX calibration algorithm for calculating the calibration coefficients. You can choose which calibration algorithm is used by selecting or clearing the Use TRAX Calibration check box. Previously, this setting was controlled in the PC-DMIS Settings Editor by modifying the DISABLETRAXCAL option.

- If you select this check box, PC-DMIS uses the TRAX calibration algorithm. The TRAX algorithm is optimized for use with scanning, so you get the best scanning results using this method. It also usually produces good results for discrete point measurements as well.

- If you clear this check box, the algorithm used depends on whether or not your machine supports the VFT (Vibration Free Transmission) calibration methodology. If it is supported, VFT is used; otherwise, the PMM algorithm is used.

The selected algorithm only applies to the currently selected tips at the time of calibration. You can change this option later for different groupings of tips as needed. The type of algorithm you chose can also be stored and recalled using named parameter sets. See the "Parameter Sets area" topic in the PC-DMIS CMM documentation.

Note that this check box does not change the distribution of discrete hits that are collected. It defines the math algorithm used to process the data after the calibration finishes. In the VFT case, it also results in a set of scans being performed after the discrete hits so that the calibration automatically includes both discrete hit data and scan data.

When to select the TRAX check box or not

The normal expected usage would be as follows:

- Do NOT select the TRAX check box on machines that support VFT so that it uses the VFT specific calibration.

- DO select the TRAX check box on non-VFT machines so that it uses the TRAX algorithm instead of the PMM algorithm.

TRAX is still available for VFT capable machines as an alternative to VFT in case of unexpected issues but is expected to be less accurate on these machines than the VFT calibration.

PMM is still available as an alternative to TRAX on non-VFT machines but is rarely used. TRAX is superior to PMM for scanning and usually just as good or better for discrete hits. There may be a few circumstances, usually limited to actual PMM machines, where the PMM algorithm might be slightly more accurate than TRAX if the inspection is only using discrete hits.

If you're unsure about when to switch calibration algorithms, consult with the creators of your particular machine. They can recommend the best practice for that machine and for particular situations.